In the Newsbin data folder, on the internal SD card, there's a folder named "NZBAutoload". If you drop NZB's into this folder, they should be picked up and processed.

If there's a password embedded in the NZB Filename, this password will shouldget added to the RAR Password manager. The password manager saves password in "Passwords.txt" also in the data folder so, you can also feed passwords to that file directly.